I have a prediction: your children will be the first generation capable of living forever. I’m a geneticist, and I’ve seen the science. I’ve worked on the science. And recently, I walked away from it.

I’m here to tell you why.

In the coming years, humanity will face the greatest decision in history: whether to become immortal. You all are the thinkers and leaders whose voices will call out in the clamor. I’m not here to persuade you. The truth is, I’m not very persuasive. I’m just a scientist. And as such, what I’d like to do today is present a series of scientific facts. All I can do is ask that you listen with an open mind. Because if you do, I believe you’ll come to the same conclusion I do: mortality is essential to our survival as a species. For me, the case for dying starts with a simple question.

Why do we die?

Why did our species evolve to live for about 70 years and then biologically self-destruct? Why not 200 years? Or 10 years? Why not forever? Why grow old at all? As you’ll soon see, some species right here on Earth don’t age.

Let’s imagine for a moment that we are mother Earth. We control the biosphere. We determine what life evolves. The ecologies around the planet dictate what organisms survive and thrive. Deep in the Mariana Trench, 36,000 feet before sea level, Xenophyophores proliferate. Researchers have found them as deep as six and a half miles below the ocean’s surface. If you brought these same organisms up to sixteen hundred feet below sea level, they couldn’t even survive. Little is known about their life cycle. All we know is that they are well adapted to the deep, just a cheetahs are fine-tuned to chase down prey on the Serengeti.

Species adapt to their environment; the fittest are selected. Over the course of millions and billions of years, evolution and the changing biosphere have genetically sculpted over ten million unique species to survive in different environments around the planet.

And all that’s fascinating—we could spend hours discussing the biodiversity of earth, what makes these organisms both unique and common. But tonight, there’s one characteristic that is of particular interest: life span.

Why do some tortoises live up to 250 years, almost four times longer than the average human? Why do rabbits only live five years? Houseflies and bees only four weeks?

There must be a reason. We’re talking about a process of evolution that has proceeded for over 3.6 billion years--since the first single-celled prokaryotes emerged on Earth.

And here’s something even more fascinating: all known mammals age, but fish and reptiles have many species that effectively don’t. They’re biologically immortal. Now obviously we consider ourselves superior to reptiles on an evolutionary basis--after all, mammals evolved from reptiles. But consider this:

As mammals age, mortality increases. Reptiles experience no increase in mortality as they age.

Most mammals have only two sets of teeth; when they’re gone, they’re gone. Reptiles replace their teeth their entire lives.

Koi, Greenland Sharks, and Bowhead whales can all live to be over 200. One species of jellyfish found in the Mediterranean and off the coast of Japan can revert to a sexually immature stage after it reproduces. Assuming it doesn’t die of disease or at the hand of a predator, it could live forever.

Here’s an example closer to home: lobsters don’t age, and in fact, they offer interesting clues about how humans could rid ourselves of aging. Lobsters don’t weaken or lose fertility with age. In fact, we suspect that older lobsters may be more fertile than younger ones. If lobsters don’t age, then why do they die (other than being placed in a pot of boiling water)? They don’t have to. We believe their life spans are only limited by their size. Lobsters grow throughout their life, adding new muscle. This requires them to shed their shell and escape, moving into a new, larger shell they create. Some large lobsters die from exhaustion during this process, others when their exoskeleton degrades and collapses entirely. But they don’t die because they’re old.

In humans, as we age our telomere ends become shorter. Think of telomeres as the plastic ends of your shoe strings, the shoe strings in this case being our chromosomes. Due to cell division, the telomere ends become shorter, leading to aging. But this doesn’t happen in lobsters--their telomeres stay the same length throughout their life thanks to an enzyme they produce called telomerase. Humans have this too, most notably in embryonic stem cells. The enzyme allows the cells to divide repeatedly and develop into a fetus. However, after that-- telomerase production pretty much stops and aging effectively begins. The only cells that feature telomerase are male germ cells and certain adult stem cells.

So if we want to live forever, telomerase feels like a good candidate to focus on, and now several studies have confirmed it. Mice genetically engineered to block the gene that produces telomerase aged much faster, dying in six months compared to the average mouse lifespan of three years. When these same genetically engineered mice were treated with a drug that activated telomerase, though, they were rejuvenated, became fertile again, and seem to reverse the effects of aging.

And that’s where I come in. Most research on telomerase has been centered around cancer, with some promising results. But for years now I’ve been studying Progeria, a genetic disease that causes premature aging and death. And in studying how to keep death from happening quicker than normal, I think I’m well on the way to discovering how to eliminate aging completely.

You see, in normal aging, when our telomeres grow short or dysfunctional, our bodies produce progerin, a protein associated with age-related cell damage. Progerin is essentially the body’s age-related self-destruct mechanism. We all produce levels of progerin, and they increase with age. In children born with Progeria, however, progerin levels are high from birth.

Having experienced loss with this terrible affliction, I have been determined to figure a way to shut down the body’s production of progerin. That, in turn, led me to telomerase, and a realization struck:

Between telomerase and progerin, we’re this close to cracking the case of aging, to unraveling its secrets and turning it off forever.

I’ll let that sink in.

The strange part is that we won’t be the first species on this planet to do so, but we will be the first to decide whether we should. And ultimately, that’s what I’m here to talk with you about. Because as amazing as the notion is—the prospect of immortality—I’m asking you to forget it. We can achieve it, yes. But I’m telling you we shouldn’t.

Let’s revisit the evolutionary history. Mammals evolved from reptiles about 200 million years ago, during the late Triassic. For perspective, dinosaurs evolved during the middle Triassic, roughly 232 million years ago and lived until about 65 million years ago. So we mammals have been around a while. And all mammals age. Aging evolved very early and had persisted for millions of years in millions of species. That’s no coincidence. More important, it leads us to only one conclusion: aging offers some evolutionary advantage.

What is that advantage? If we stop aging, what are we giving up? That’s what’s at stake. At first glance, immortality seems like a no-brainer, but it’s not that simple.

In a recent study, researchers ran computer models with two human populations: one immortal, the other mortal. In every simulation, over generations, the mortal cohort always had a higher survival rate. Why?

Adaptability.

You see, the mortals were forced to reproduce. Reproduction brings genetic diversity. It brings mutations. As environments change, so must we to have a chance at survival. As the immortal cohort increased in population, resources became increasingly scarce. Younger generations were competing with established members. The cycle of life--of birth, aging, and dying--is evolution’s way of tuning our species to survival, of introducing new adaptations and eliminating features no longer needed for the environment. New generations provide new energy, new ideas. The proof is right there in front of us. Consider the species we’ve discussed. Turtles. Koi. Sharks. Lobsters. Those immortal jellyfish. Think about how much they’ve changed in the last 100 million years. And think about humans--a species that has only existed for two-hundred thousand years. We’ve evolved to adapt and aging is essential to that.

But, wait--can’t we assume the role of evolution? If we can genetically engineer ourselves to become immortal, we certainly have the power to adapt our genomes to the environment. In fact, we can do it much faster than evolution, which creeps along. We can pinpoint genes that offer an advantage and roll them out in days and weeks, not thousands of years. Surely that’s a better way.

Therein lies the folly I want to bring you to:

Who decides?

Who decides which of us becomes immortal? Who decides which genetic adaptations we adopt? Immortality represents a singularity in human science, but more importantly a paradigm shift in our society. We are all subject to nature. We all live on the same earth and are governed by the same whims of evolution. We have no one to blame for our genetic fate.

But what if we did?

What would people be willing to do to live forever? Or to receive the genetic gifts given to a neighbor and denied to them? Unequal societies breed nasty conflicts—the history of the 20th Century is testament to this. With all this advancement, would we see the first genetic civil war?

My goal, tonight, is to ensure that we don’t.

Because I’m describing a war that we can stop. A war that never has to happen. And all you have to do so that millions aren’t killed is die. Don’t do it for your sake. Do it for your children’s sake. Do it so that they will have a chance to live and die, just like you, and so their children can as well. Do it so none of them will get to play God, so none of them will ever be denied something they can’t live without, literally.